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System Memory Map
Memory address range Usage
000000h to 09FFFFh
640KB base memory
0A0000h to 0BFFFFh
128KB video memory
0C0000h to 0C7FFFh
32KB video ROM BIOS
0C8000h to 0DFFFFh
O0E0000h to 0FFFFh
32KB
external adapter ROM BIOS
128KB system ROM BIOS
100000h to FDFFFFh
Extended memory
FE0000h to FFFFFFh
128KB
of ROM remapped from 0E0000h to
0FFFFFh
System I/O Address Map
Hex address
Assigned device
000 - 01F
DMA controller 1,8237
020 - 03F
Interrupt controller 1,8259
Chip set configuration registers
022 - 024
034, 038B, 03V
AD12 chipset configuration registers
040 - 05F
Timer, 8254
060 - 06F
Keyboard controller, 8042
070 - 07F
080 - 09F
0A0 - 0BF
NMI (non-maskable interrupt)
DMA page register, 74LS612
Interrupt controller 2,8259A
0C0 - 0DF
DMA controller 2,8237
0F0
Clear math coprocessor
0F1
Reset math coprocessor
0F8 - 0FF
Math coprocessor
1F0 - 1F8
200 - 207
278 - 27F
Hard disk
Game I/O
Parallel printer port 2
280 - 2DF
Alternate enhanced graphics adapter
A-14
Specifications